LEC 18: Vessels (Arteries & Veins, Lymphatics)

Vocabulary flashcards covering vessels, their structures, functions, and major circulation concepts from the notes.

Arteries

Blood vessels that carry blood away from the heart; have thicker tunica media and more elastic and collagen fibers.

Capillaries

Microscopic vessels where exchange between blood and tissues occurs; three types: continuous, fenestrated, and sinusoid.

Veins

Blood vessels that carry blood toward the heart; have thinner walls, larger lumen, and often valves.

Lumen

The space inside a blood vessel through which blood flows.

Tunica intima

Innermost layer of a vessel wall, composed of endothelium and subendothelial tissue.

Endothelium

Simple squamous epithelial lining of the tunica intima.

Subendothelial layer

Areolar connective tissue beneath the endothelium.

Tunica media

Middle layer with circular smooth muscle and elastic fibers; controls vessel diameter.

Elastic fibers

Elastic proteins in the tunica media that help vessels recoil.

Smooth muscle cells

Muscle cells in the tunica media that cause vasoconstriction or vasodilation.

Vasoconstriction

Narrowing of a vessel due to smooth muscle contraction.

Vasodilation

Widening of a vessel due to smooth muscle relaxation.

Tunica externa

Outermost vessel layer made of connective tissue; anchors vessel and may contain vasa vasorum.

Vasa vasorum

Small arteries that supply the walls of large vessels.

Companion vessels

Arteries and veins lying next to each other serving the same body region.

Artery vs vein wall structure

Arteries: thicker tunica media; veins: thicker tunica externa and larger lumen; veins often have valves.

Continuous capillaries

Capillaries with complete endothelial lining and intercellular clefts; restrict large particles.

Fenestrated capillaries

Capillaries with endothelial pores (fenestrations) allowing movement of small plasma proteins.

Sinusoids (discontinuous capillaries)

Capillaries with large gaps and incomplete basement membrane; permit transport of large substances.

Capillary bed

Group of capillaries fed by a metarteriole; includes true capillaries and a thoroughfare channel.

Metarteriole

A vessel branch of an arteriole that feeds the capillary bed.

Thoroughfare channel

Distal part of the capillary channel that connects to postcapillary venule; lacks smooth muscle.

True capillaries

Capillaries branching from the metarteriole where exchange occurs.

Precapillary sphincter

Smooth muscle ring at the origin of true capillaries that regulates entry of blood into capillaries.

Vasomotion

Rhythmic contraction and relaxation of precapillary sphincters regulating capillary flow.

Perfusion

Amount of blood entering capillaries per unit time per gram of tissue.

Venous valves

Valves in veins that prevent backflow and pooling; formed by tunica intima with elastic and collagen fibers.

Pulmonary circulation

Right ventricle pumps deoxygenated blood to the lungs; low pressure and slower flow for gas exchange.

Systemic circulation

Left ventricle to the rest of the body; higher pressure to deliver oxygen and nutrients.

Systemic blood reservoir

Most of the blood is held in systemic veins at rest (about 70%).

Hepatic portal system

Veins draining digestive organs feed the hepatic portal vein to the liver for processing.

Hepatic portal vein

Carries nutrient-rich blood from digestive organs to the liver.

Hepatic veins

Drain blood from the liver to the inferior vena cava.

Celiac trunk

Unpaired abdominal aorta branch below the diaphragm; branches include left gastric, splenic, and common hepatic arteries.

Superior mesenteric artery

Unpaired artery supplying most of the small intestine and parts of the large intestine.

Inferior mesenteric artery

Unpaired artery supplying distal large intestine and rectum.

Left gastric artery

Branch of the celiac trunk supplying the stomach and lower esophagus.

Hepatic artery proper

Branch of the common hepatic artery supplying the liver and gallbladder.

Gastroduodenal artery

Branch of the common hepatic artery supplying the stomach, duodenum, and pancreas.

Superior mesenteric arteries branches

Branches supplying intestinal arteries, middle colic, right colic, and ileocolic regions.

Inferior mesenteric artery branches

Branches supplying left colic, sigmoid arteries, and superior rectal region.

Hepatic sinusoids

Specialized capillaries in the liver where exchange with hepatocytes occurs.

Vertebral arteries

Arise from the subclavian arteries; ascend through cervical vertebrae to the brain; join to form the basilar artery.

Internal carotid arteries

Supply brain; give rise to anterior and middle cerebral arteries and ophthalmic artery.

External carotid arteries

Supply structures external to the skull; give branches such as superior thyroid, lingual, facial, and maxillary.

Circle of Willis

Cerebral arterial circle that equalizes brain blood pressure and provides collateral pathways.

Anastomosis

Connection between vessels allowing alternate routes for blood flow.

Aorta and arch branches

Aorta gives rise to brachiocephalic trunk, left common carotid, and left subclavian; arch becomes descending aorta.

Brachiocephalic trunk

Artery that splits into right common carotid and right subclavian arteries.

Common iliac arteries

Divide into internal and external iliac arteries; internal supplies pelvis, external to lower limb.

Superior vena cava

Large vein formed by the union of the brachiocephalic veins; returns blood to the right atrium.

Coronary sinus

Vein draining the heart muscle into the right atrium.

Azygos system

Network of veins (including hemiazygos) draining thoracic wall and abdominopelvic structures into the superior vena cava.

Internal thoracic vein

Drains anterior chest wall into the brachiocephalic vein.

Superior phrenic arteries

Arteries arising from the descending thoracic aorta to supply the diaphragm.

Inferior phrenic arteries

Arteries arising from the descending abdominal aorta to supply the diaphragm.

Musculophrenic arteries

Branches of the internal thoracic artery supplying the diaphragm and intercostal spaces.

Pericardiacophrenic arteries

Branches of the internal thoracic artery supplying the pericardium and diaphragm.

Internal thoracic artery

Artery supplying the anterior thoracic wall and mammary gland; gives anterior intercostals and musculophrenic branch.

Great saphenous vein

Long superficial vein running along the medial leg to join the femoral vein.

Small saphenous vein

Superficial vein along the lateral/posterior leg draining into the popliteal vein.

Brachial artery

Main artery of the upper arm; continuation of the axillary artery beyond the teres major.

Radial and ulnar arteries

Forearm arteries that form the deep and superficial palmar arches; supply the hand.

Deep palmar arch

Palmar arterial arch largely formed by the radial artery.

Superficial palmar arch

Palmar arterial arch largely formed by the ulnar artery.

Dorsalis pedis

Continuation of the anterior tibial artery over the ankle to the foot.

Plantar arches

Arterial arches on the plantar aspect of the foot formed by dorsalis pedis and lateral plantar arteries.

Hepatic portal vein

Portal vein carrying nutrient-rich blood from digestive organs to the liver.

Liver sinusoids

Capillary-like vessels in the liver where exchange with hepatocytes occurs.

Dural venous sinuses

Large venous channels between layers of dura mater that drain brain blood and CSF to the internal jugular veins.